DAR ES SALAAM, Feb 24 (Reuters) - Homemade bombs went off near a cathedral and a restaurant popular with tourists on Monday on the semi-autonomous and mainly Muslim Zanzibar islands, where sectarian tensions have been mounting, a police spokesman said.

There were no casualties, Zanzibar police spokesman Mohammed Mhina said. But one tour operator on the island, who asked not to be identified, said at least one person had been wounded.

The Indian Ocean islands are a growing headache for the Tanzanian government because of religious tensions and deep social and economic divisions. Last year there were several attacks on Christian leaders, tourists and churches.

"There were two explosions which occurred at around 1 p.m. this afternoon. The explosions were caused by makeshift bombs," the police spokesman said, without saying who was behind the attacks.

One bomb went off next to an Anglican cathedral near Zanzibar's capital Stone Town, while another at about the same time exploded at a restaurant in the city popular with tourists, he added.

Many Muslims living along Tanzania's coast feel marginalised by the secular government, providing fertile recruitment grounds for Islamist groups such as al Shabaab, which operates in Somalia further north on Africa's east coast.

Tanzanian President Jakaya Kikwete has warned that religious tensions threaten peace in the nation of 45 million people.

Two Christian leaders were killed in Zanzibar last year in separate attacks and there have been arson attacks on churches.

In September, a Roman Catholic priest was the target of an acid attack, while a month earlier two men threw a corrosive liquid over two British teenagers in Zanzibar.

The incidents have hit Tanzania's image as a tourist-friendly destination, hurting a vital industry.

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